<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <script>
    onload = function() {
      let t = document.getElementById("tid");
      t.onclick= function() {
        alert(45455454);
      }
    }
  </script>
</head>
<body>
  <input type="button" value="点击" id="tid"/>
</body>
</html>